During extreme storms, ocean waves may be as high as 20 meters or as high as five-story buildings.
More than being the only product of our time systems, waves are critical for shipping oceans, beach stability, coastal floods or floods, and determining the design of coastal and coastal structures.
But our new research, published in Science, shows that these waves and the winds they generate are increasing in size and doing so in the last 30 years.
These new measurements show that global mean waves conditions increase, but more importantly, extreme waves conditions increase even faster with the greatest increases occurring in the Southern Ocean.
We found that the extreme winds in the South Ocean increased by about 1.5 meters per second or 8 percent over the last 30 years. Similarly, extreme waves in the same region increased by 30 centimeters or 5 percent. In general, winds are rising faster than the waves.
In addition to the rise of the Southern Ocean, extreme winds have also increased in the equatorial Pacific and Atlantic and North Atlantic for about 0.6 meters per second during the 30-year period.
These changes in the wind of the ocean and the waves are determined by creating and analyzing the satellite measurement of wind speed and wave height.
We used data from a total of 31 satellites that were in orbit between 1985 and 2018. For more than thirty years, these satellites have made approximately 4 billion measurements of wind speed and wave height.
Although the data is huge, be useful all the satellites needed to be very precisely calibrated. This was done by comparing satellite measurements with more than 80 ocean floating vessels all over the world. This is the largest and most accurate database of its kind ever compiled.
More importantly, within the combined database, there are three different forms of satellites – altimeters, radiometers and scatterometers. They used different methods for measuring the waves of the ocean, so their combination provides even more extensive data.
Increasing the height of the extreme wave is less uniform than the winds. Despite the rise of the Southern Ocean, the heights of extreme waves are rising in the North Atlantic. The rate of increase in wind speed and wave height are shown in the graphs above.
Although increases of 5 per cent for waves and 8 per cent for winds may not look as much if sustained in the future, such changes in our climate will have great consequences. Potential impacts of climate change on sea level are known. What most people do not understand is that current floods are caused by storms and waves of storm-related waves.
Increased sea level makes these wind and wave events more serious and more frequent. Increasing the height of the wave and other properties, such as the direction of the wave, will further increase the likelihood of flooding the coastline. Changes such as these will also cause increased coastal erosion, putting at risk coastal settlements and infrastructure.
We still do not know if historical increases will take place in the future. One of the important uses of the wide satellite database will be to calibrate and confirm the next generation of global climate models that now include the prediction of an ocean wave. The early results of such models give similar results to the historical record and in particular indicate changes in the Southern Ocean.
Changes in the Southern Ocean are important because this is the origin of sweating that dominates the wave climate of the South Pacific, the South Atlantic and the Indian Ocean, and determines the stability of the beaches for most of the southern hemisphere.
Changes in the Southern Ocean can have impacts that are felt around the world, with storm waves increasing coastal erosion, and placing coastal settlements and infrastructure at risk.
International research teams, including the University of Melbourne, are now working to develop the next generation of global climate models for designing changes in winds and waves over the next 100 years.
A better understanding of how much of this change is due to long-term climate change and how much is due to multiple decay fluctuations or cycles.
This article was first published on Execution. Read the original article.
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